A 35-year-old man who had been in coma and vegetative state for 15 years after a car accident has shown signs of consciousness,

This happened after a vagus nerve stimulator was implanted into his chest, researchers said Monday.

The outcome, reported in the U.S. journal Current Biology, challenged the general belief that disorders of consciousness that persist for longer than 12 months are irreversible.

“By stimulating the vagus nerve, we show that it is possible to improve a patient’s presence in the world,” Angela Sirigu of Institut des Sciences Cognitives Marc Jeannerod in Lyon, France, said in a statement.

The treatment, known as vagus nerve stimulation (VNS), is already in use for epilepsy and depression.

The vagus nerve connects the brain to many other parts of the body, including the gut, and it’s known to be important in waking, alertness, and many other essential functions.

To test the ability of VNS to restore consciousness, the researchers wanted to select a difficult case to ensure that any improvements couldn’t be explained by chance.

They looked to a patient who had been lying in a vegetative state for more than a decade with no sign of improvement.

After one month of vagal nerve stimulation, the patient’s attention, movements and brain activity significantly improved, they reported.

The man began responding to simple orders that had been impossible before. For example, he could follow an object with his eyes and turn his head upon request.

His mother reported an improved ability to stay awake when listening to his therapist reading a book.

After stimulation, the researchers also observed responses to “threat” that had been absent. For instance, when the examiner’s head suddenly approached the patient’s face, he reacted with surprise by opening his eyes wide.

After many years in a vegetative state, he had entered a state of minimal consciousness, the researchers said.

Recordings of brain activity revealed major changes in areas of the brain involved in movement, sensation, and awareness, and also showed increased brain functional connectivity.

A PET scan showed increases in metabolic activity in both cortical and subcortical regions of the brain, too.

The researchers said the findings showed that the right intervention can yield changes in consciousness even in the most severe clinical cases.

“Brain plasticity and brain repair are still possible even when hope seems to have vanished,” Sirigu said.

The researchers are now planning a large collaborative study to confirm and extend the therapeutic potential of VNS for patients in a vegetative or minimally conscious state.

In addition to helping patients, Sirigu said the findings will also advance understanding of “this fascinating capacity of our mind to produce conscious experience.” (Xinhua/NAN)